Method for determining effective content of formaldehyde condensate bactericide

The invention relates to a method for determining the effective content of a formaldehyde condensate bactericide, comprising the following steps: (1) adding phosphoric acid to a formaldehyde condensate bactericide to obtain a mixed liquid, and then distilling the mixed liquid to obtain a formaldehyde gas; (2) absorbing the formaldehyde gas obtained in the step (1) by the use of water, regulating the pH by adding sodium hydroxide, and then adding excess sodium sulfite to obtain an adduct of formaldehyde and sodium hydroxide; (3) dropwise adding sulfuric acid to adjust pH of the solution to thepH before sodium sulfite is dropwise added, recording the dropwise adding amount of sulfuric acid, converting to obtain the amount of formaldehyde obtained by distillation, and then converting to obtain the effective content of the formaldehyde condensate bactericide. In comparison with the prior art, the method of the invention has the following advantages: relative standard deviation of the formaldehyde content in the f